This disclosure relates to gas turbine engines, and more particularly to adjusting vane angles of variable vanes in a gas turbine engine.
Gas turbine engines typically include a compressor section, a combustor section, and a turbine section. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.
Some areas of a gas turbine engine may include variable vanes that are circumferentially spaced apart from each other. The compressor, for example, may include multiple stages of variable vanes that are axially separated from each other by rotor blades. In some compressor designs, the stages of variable vanes are mechanically connected to respective synchronizing rings (sync-rings) by vane arms. The sync-rings rotate clockwise and counterclockwise circumferentially around the compressor case to pivot the vane arms and set vane angles that optimize engine operability (e.g., preventing stalling and/or buffeting) and engine performance (e.g., maximizing thrust and/or minimizing fuel consumption). During operation, an actuation system drives the sync-rings.
Variable vane actuation systems have traditionally relied on linked multistage adjustment structures that, when actuated, simultaneously adjust each of a plurality of stages of variable vanes through a shared torque box as a single point of actuation. In such arrangements, adjustment of a first stage of variable vanes necessarily also adjusts the other linked stages, because as a given sync-ring is rotated in a circumferential direction around the engine, the other sync-rings are also circumferentially rotated in a pre-established proportion. Separate actuators have also been proposed.